Ship construction

ABSTRACT

A ship construction for operation in ice-covered waters wherein the hull lies substantially below the water surface with a minor portion forming the superstructure rising above this surface, characterized in that forward and aft superstructure units are provided to facilitate reserve buoyancy and longitudinal stability of the ship with each of the units extending upwardly from the hull and each having a narrow width constricted base portion with the sides of each unit flaring upwardly and outwardly of this base portion, the ship being maintained at substantially the level of these constricted base portions thereby facilitating little resistance by the ship&#39;&#39;s passage through the ice which is partly broken up by the stem of the ship.

tlnited States Patent [191 Sandnaes 1451 Feb. 18, 1975 SHIP CONSTRUCTION [76] Inventor: Per Christian Sandnaes,

Kaldbakkfaret l3, Oslo, Norway [22] Filed: Jan. 22, 1973 [21] Appl. No.: 325,552

Related US. Application Data [63] Continuation of Ser. No. 126,859, March 22, 1971,

abandoned.

[30] Foreign Application Priority Data Mar. 20, 1970 Norway 1059/70 [52] US. Cl. 114/41 [51] Int. Cl B63b 35/08 [58] Field of Search 114/40-42, 114/665 H, 16 R [56] References Cited UNITED STATES PATENTS 1,500,000 7/1924 Lake 114/40 3,063,397 11/1962 Boericke 114/16 R FOREIGN PATENTS OR APPLICATIONS Norway 114/42 Primary Examiner-Trygve M. Blix Assistant Examiner-Sherman D. Basinger Attorney, Agent, or FirmWatson, Cole, Grindle & Watson [5 7] ABSTRACT A ship construction for operation in ice-covered waters wherein the hull lies substantially below the water surface with a minor portion forming the superstructure rising above this surface, characterized in that forward and aft superstructure units are provided to facilitate reserve buoyancy and longitudinal stability of the ship with each of the units extending upwardly from the hull and each having a narrow width constricted base portion with the sides of each unit flaring upwardly and outwardly of this base portion, the ship being maintained at substantially the level of these constricted base portions thereby facilitating little resistance by the ships passage through the ice which is partly broken up by the stem of the ship.

7 Claims, 3 Drawing Figures SHIP CONSTRUCTION This is a continuation of application Ser. No. 126,859 filed Mar. 22, 1971 and now abandoned.

This invention relates to a ship construction having tant.

Ship constructions which include a submersed main hull are already known. The purposes of these designs have been to reduce wavemaking resistance or waveinduced vessel motion for passenger ships.

This invention proposes a hull shape similar to what is already known and sometimes referred to as a semisubmarine. It includes a main hull which can be submersed below the water surface, and superstructures which rise above water. All parts are shaped to minimize ice resistance and to enhance the vessels capability of cargo transportation in ice-covered waters.

By making the superstructures narrower at the design waterline than above, ice-resistance is minimized without reducing reserve buoyancy.

The main hull carries two superstructures, one near to the bow and one close to the stern. Either one or both of these superstructures of the main hull may be equipped with special devices for facilitating steering in ice. The stem may extend forward under the water surface and terminate in a sharp point well below maximum draft waterline. Moving aft from this sharp point, the upper part of the stem rises gradually at a fairly small angle with the waterline until it curves smoothly upward into the forward edge of the superstructure, which is shaped for easy passage through broken ice. Thus shaped, the bow breaks the ice by forcing it upwardly and pushes the broken pieces out of the way like a gigantic snow plow. The lower part of the bow is shaped for conventional downward ice-breaking. Combined with trim tanks of sufficient capacity, forward draft can be adjusted to put either the upper, upward ice-breaking part of the bow or the lower, conventional part into action.

This and additional features will be illustrated by the following description of the drawings.

FIG. 1 is a side view of a cargo vessel which is shaped in accordance with the invention.

FIG. 2 is a plan view of the same vessel.

FIG. 3 is a transverse section at one of the superstructures through a similar vessel.

The main hull is designated 1 and the forward and aft superstructures are designated 2 and 2', respectively. In addition to crew quarters, these superstructures may contain the navigation bridge, accesses to the submersed main hull, ventilation, air intakes, smoke channels, and stacks, heliport, etc. One of the main purposes of these superstructures is to provide the vessel with the necessary safe amount of reverse buoyancy, draft control and the ability to resist large ice-induced trim moments.

The added width of the superstructures above water prevents the vessel from being squeezed down by pack ice. The forward end of the superstructure may be shaped to give the moving vessel lift from passing ice and water whenever the ice-breaking process at the stem tends to force the vessel down.

FIGS. 1 and 2 show the bow with the sharp point 6 mentioned earlier and the smooth transition 7 of the upper part of the stem into forward superstructure 2. As indicated in FIG. 3, both the forward and the aft superstructures are narrow as at 8 at the design waterline in order to minimize ice resistance.

The vessel is provided with propulsion machinery 3, rudder 4 and propellers 5. Parts of the propulsion machinery could possibly be located in the superstructures.

FIG. 3 shows the main hull constructed with an outer shell 9,, and an inner shell 9 The space between the two shells is mainly used for ballast. This construction increases the strength of the vessel and reduces the risk of oil pollution of the-environment in case of hull damage. Also, the double shell ballast tanks may be used for draft, trim, and list control. i

In FIGS. 1-3, VL designates the normal operating waterline for travelling through ice-covered waters. In order to get the vessel down to this waterline, the pure ballast tanks of the main hull are flooded. With these tanks empty, the vessel should be able to travel fully loaded at waterline VL This waterline or intermediate waterlines could occasionally be more advantageous than VL, for instance when passing through open or shallow water.

When carrying crude oil, the vessel willprobably need some high-density, permanent ballast at the bottom level in order to obtain sufficiient submergence and transverse stability.

One basic idea of the invention is that transverse stability is obtained independent of transverse waterplane inertia. Thus, from a stability point of view, waterline breadth is unimportant. In case cargoes with higher density than crude oil, for instance iron ore or even water, the vessel will probably be able to obtain sufficient stability and submergence without permanent ballast.

Even though, preferred configurations are described above and shown in the drawings, numerous modifications can be made without departing from the basic idea of this invention.

I claim:

1. A ship construction of supertanker size for operation in ice-covered waters comprising a main hull with forward and aft superstructure units extending upward therefrom and being separated from one another to facilitate a reserve buoyancy and longitudinal stability of the ship, the width of said main hull being substantially greater along its length than the width of each said unit, said forward unit being spaced rearwardly from the ships bow, said bow terminating in a point and having side surfaces extending between said bow point and said forward unit, said surfaces intersecting along a straight line extending from a lower portion of said forward unit to said bow point and sloping downwardly away from one another, said forward unit having side surfaces sloping forwardly and intersecting along a line smoothly curving into and forming an extension of said straight line, the ship being designed to travel fully loaded in open sea at a level (VU) located just below said bow point, each of said forward and aft units having side walls extending upwardly from said main hull and inwardly toward one another and thereafter outwardly away from one another with smooth curved sections respectively interconnecting said inward and said outward extensions thereby defining narrow width con-' stricted base portions for both said units, said main hull having spaced outer and inner shells, ballast means defined by the space between said outer and inner shells in said main hull for maintaining the ship at substantially a level (VL) of said constricted base portions thereby facilitating little resistance by the ships passage through the ice which is partly broken up by said side surfaces of said bow, the level (VL) being higher than the level (VL 2. The ship construction according to claim 1 wherein said ballast means includes ballast tanks in said main hull for maintaining the ship at substantially the level of said constricted portions and at said level (VL suited for navigation in open sea.

3. The ship construction according to claim 1 wherein a rudder is provided on the ship for steering it through an ice field.

4. A ship construction according to claim 3 wherein the ships stern is constructed in suchc a form so as to protect the rudders and propellers of the ship from contacting the ice.

5. The ship construction according to claim 1 wherein said aft superstructure unit is forwardly spaced from the stern of the ship and is arranged at a certain distance from the forward superstructure unit.

6. A ship construction according to claim I wherein said ballast means are capable of being adjusted to provide stability of the ship.

7. A ship construction according to claim 1 wherein the lower portion of said bow has a forwardly pointed flared form suited for sea-going travel as well as breaking ice. 

1. A ship construction of supertanker size for operation in icecovered waters comprising a main hull with forward and aft superstructure units extending upward therefrom and being separated from one another to facilitate a reserve buoyancy and longitudinal stability of the ship, the width of said main hull being substantially greater along its length than the width of each said unit, said forward unit being spaced rearwardly from the ship''s bow, said bow terminating in a point and having side surfaces extending between said bow point and said forward unit, said surfaces intersecting along a straight line extending from a lower portion of said forward unit to said bow point and sloping downwardly away from one another, said forward unit having side surfaces sloping forwardly and intersecting along a line smoothly curving into and forming an extension of said straight line, the ship being designed to travel fully loaded in open sea at a level (VL2) located just below said bow point, each of said forward and aft units having side walls extending upwardly from said main hull and inwardly toward one anotHer and thereafter outwardly away from one another with smooth curved sections respectively interconnecting said inward and said outward extensions thereby defining narrow width constricted base portions for both said units, said main hull having spaced outer and inner shells, ballast means defined by the space between said outer and inner shells in said main hull for maintaining the ship at substantially a level (VL1) of said constricted base portions thereby facilitating little resistance by the ship''s passage through the ice which is partly broken up by said side surfaces of said bow, the level (VL1) being higher than the level (VL2).
 2. The ship construction according to claim 1 wherein said ballast means includes ballast tanks in said main hull for maintaining the ship at substantially the level of said constricted portions and at said level (VL2) suited for navigation in open sea.
 3. The ship construction according to claim 1 wherein a rudder is provided on the ship for steering it through an ice field.
 4. A ship construction according to claim 3 wherein the ship''s stern is constructed in suchc a form so as to protect the rudders and propellers of the ship from contacting the ice.
 5. The ship construction according to claim 1 wherein said aft superstructure unit is forwardly spaced from the stern of the ship and is arranged at a certain distance from the forward superstructure unit.
 6. A ship construction according to claim 1 wherein said ballast means are capable of being adjusted to provide stability of the ship.
 7. A ship construction according to claim 1 wherein the lower portion of said bow has a forwardly pointed flared form suited for sea-going travel as well as breaking ice. 